TWI647260B - High Permselectivity of PVA/GA/CS-M+Membrane for Dehydration of Organic Solvent - Google Patents

Abstract

Heavy metal ions (M ⁺ ) such as Ag ⁺ , Cu ²⁺ , Fe ³⁺ are used to chelate CS (chitosan) as a precursor, mixed with PVA (polyvinyl alcohol), and then added with GA (glutaraldehyde). The crosslinking agent can form a PVA/GA/CS-M ⁺ pervaporation film which has high mechanical strength, thermal stability and exhibits excellent permeability and selectivity for dehydration of an organic solution.

Description

High permeability and high selectivity PVA/GA/CS-M+ pervaporation film for dehydration of organic solutions

The present invention relates to a pervaporation film, and more particularly to a permeation evaporation film for high permeability and high selectivity for dehydration of an organic solution and a preparation method thereof.

Isopropanol (IPA) is used in the production of acetone, isopropyl ester, isopropylamine and other raw materials. It is also widely used in pharmaceuticals, pesticides, cosmetics, plastics, perfumes, coatings, etc., and as a cleaning agent and oil in semiconductors. Solvents such as gums, waxes and cosmetics. Ethanol (Ethol, EtOH) can be used to make acetic acid, acetaldehyde, ether, ethyl acetate, ethylamine, etc. It is also a raw material for the production of medicines, cosmetics, dyes, paints, detergents, beverages, flavors, and fuels for vehicles. Acetone (Acetone) can be used in the manufacture of bisphenol A, methyl methacrylate, acetone cyanohydrin, methyl isobutyl ketone, etc., as well as pharmaceuticals, cosmetics, building materials, paints, plastics, fibers, gunpowder, Resin, rubber, photographic film, etc. The reuse of organic solvents clearly contributes to economic advantages and environmental protection, and dehydration of organic solvents is particularly important in the development of thin film technology. The use of a pervaporation membrane to separate the alcohol/water mixture is superior to conventional distillation methods because it overcomes the azeotropy of the alcohol/water. In particular, pervaporation membrane separation is an efficient process for energy saving since it does not require operation at high temperatures.

The dissolution-diffusion model has undoubtedly been accepted to describe the transport phenomena in pervaporation membrane technology. The structure of the film can greatly affect the dissolution-diffusion behavior of the solution, thereby affecting the transmission efficiency.

Lu et al. proposed a hydration of the film during pervaporation as a dynamic process involving adsorption-desorption equilibrium. Since the hydrophilic film can make the water easy to be absorbed-diffused, the transfer efficiency can be improved. Therefore, the water absorption property of the hydrophilic membrane becomes a key factor in the design of the pervaporation separation membrane.

PVA is a highly hydrophilic polymer with good film forming properties and chemical resistance, and is a preferred material for pervaporation dehydration. However, due to the presence of its hydroxyl group, its swelling phenomenon in aqueous nighttime is difficult to be masked. By introducing a crosslinking agent, the intermolecular structure of the PVA-based film can enhance the formation of strong covalent bonds between the polymer chains, rather than weaker hydrogen bonds, thereby increasing mechanical strength and greatly improving stability. . The pervaporation test is used to evaluate the pervaporation separation efficiency of the film, and the physical and chemical properties of the obtained film are measured according to the contact angle, the degree of expansion, the mechanical properties, and the thermal stability. However, although the cross-linking agent can make the structure of the membrane relatively stable, it will consume the hydrophilic group of the polymer chain. It is known that the cross-linking agent can form a relatively stable membrane structure for the PVA matrix, and also brings about water penetration. The negative effect is that the formation of the crosslinker will consume hydroxyl groups in the PVA polymer. Therefore, how to improve the pervaporation film so that it can be used for dehydration of an organic solution can effectively promote the water transmittance without losing its selectivity, which is an urgent problem to be solved.

SUMMARY OF THE INVENTION An object of the present invention is to provide a permeation evaporation film for high permeability and high selectivity for dehydration of an organic solution and a preparation method thereof, which can effectively promote water transmittance without losing its selectivity.

In order to achieve the foregoing object, the present invention is a high permeability and high selectivity pervaporation film preparation method for dehydration of an organic solution, which comprises the following steps: preparing a material: preparing polyvinyl alcohol (PVA) (Mw ∼ 125,000), chitosan (CS) (Mw ~ 30,000), 25 weight percent glutaraldehyde (GA) and 99 weight percent isopropanol, ethanol and acetone; 5 g of CS dissolved in 45 g of deionized water, stirred at room temperature for 8 hours, used Forming a solution; adding different weights of heavy metal salts such as silver nitrate, copper nitrate, iron nitrate, etc. to the solution to form liquid A, and continuing to stir; dissolving 5 g of PVA in 45 g of deionized water at 70 ° C After stirring for 24 hours, liquid B was formed, and liquids A and B were thoroughly mixed and stirred for 2 hours to form a mixed solution C; then the mixed solution C was poured into a polyethylene petri dish, and glutaraldehyde was added thereto. The PVA/GA/CS-M ⁺ pervaporation film was formed by drying in a oven at a specified temperature for 1 day.

According to one embodiment of the invention, the unit weight is 5 g and the nine unit weight is 45 g.

According to another embodiment of the present invention, the chitosan (CS) is dissolved in ionic water at room temperature for 8 hours, and the polyvinyl alcohol (PVA) is dissolved in deionized water for 24 hours.

According to another embodiment of the invention, the oven has a specified temperature of 40 °C.

A pervaporation film is formed in accordance with the preparation method of the present invention.

The invention discloses a high permeability and high selectivity pervaporation film for dehydration of an organic solution and a preparation method thereof, the preparation method comprising:

Preparation materials: polyvinyl alcohol (PVA) (Mw ~ 125,000), chitosan (CS) (Mw ~ 30,000), 25% by weight of glutaraldehyde (GA), and 99% of isopropanol (IPA), ethanol (EtOH) and acetone (Acetone). All chemical reagents are reagent grade and require no further purification.

Preparation process: 5 g of CS is dissolved in 45 g of deionized water, stirred at room temperature for 7 to 10 hours, especially for 8 hours, and then different weights of silver, copper, iron ions, that is, nitrates are added respectively. In the former solution, liquid A was formed and stirring was continued, in other words, the weight ratio of CS to deionized water of liquid A was 1:9. 5 g of PVA is dissolved in 45 g of deionized water and stirred at 70 ° C for 20 to 24 hours, especially 24 hours, to form liquid B, in other words, the weight ratio of liquid B to PVA and deionized water is 1:9. The liquids A and B were thoroughly mixed and stirred for 2 hours to form a mixed solution C. Then, the mixed solution C was poured into a petri dish made of polyethylene, dried in an oven at a specified temperature of 40 ° C for 1 day, and glutaraldehyde was added to form PVA/GA/CS-M ⁺ (M ⁺ represents heavy metal ions). The pervaporation film, wherein the temperature of the oven is not too high or too low, so as not to affect the formation of the present invention.

The pervaporation film produced by the present invention measures the contact angle, the degree of swelling, the mechanical properties and the thermal stability. Further, the pervaporation film of the present invention can respectively recognize the functional groups of the present invention by Fourier transform infrared spectroscopy (FTIR) analysis, which is explained below.

Fourier transform infrared spectroscopy (FTIR): The functional groups of the pervaporation film and the identification of their interactions were expressed by FTIR spectroscopy (Perkin-Elmer spectrometer, FTS-1000). Measured in the infrared region of the wavelength region 450-4000 cm ^-1 .

Thermogravimetric analysis (TGA, Thermogravimetric analysis): TGA test was performed using Perkin-Elmer Pyis-17GA at a scan rate of 10 °C/min under an oxygenation environment at a temperature range of 25-800 °C.

Scanning Electron Microscopy and Energy Dispersive Spectroscopy (SEM & EDS): Scanning electron microscopy was used to observe the surface morphology of the film and to study the energy dispersion spectrum of the composition.

Atomic force microscopy is used to detect the roughness and microscopic surface structure of the film.

Contact angle: The surface of the sample exhibited characteristics of the chemical and physical properties of the pervaporation film by a contact angle analyzer (FTA125 contact angle analyzer). The contact angle of water is carried out by placing distilled water droplets on the surface of the pervaporation film.

Swelling degree: The obtained inventive product was cut into a 2 cm × 2 cm sample, placed in a precision balance (Ab304-S/FACT) to obtain its weight (Wd, dry film weight), and the dry film was placed in various ratios of 100 g. After maintaining the water/isopropanol mixture for 24 hours, the weight (Ws) of the wet film was obtained with a precision balance. The degree of swelling of the film is calculated by the following formula (1): DS (%) ) 100% (1)

Pervaporation experiment: Pervaporation dehydration measurements were carried out in the apparatus as described above. The feed zone pressure was measured by a mercury pressure gauge and the pressure was maintained at a vacuum of about 2 torr using a vacuum pump, the effective area in contact with the feed mixture was about 7 cm ² , and the mixture was passed through an electronically controlled thermometer. The feed temperature was maintained at 30 °C. The composition of the permeate was measured with a refractometer (RX-5000α). The pervaporation separation efficiency of the present invention was evaluated based on the amount of permeation and the separation factor (α sep ). (2) (3)

Where W is the mass of the permeate (kg), A is the effective area (m ² ) of the pervaporation film, t is the time (h) of the permeation, P w and P IPA , P EtOH , P Acetone are the permeate water and Percentage by mass of isopropanol, ethanol, acetone, and the like. F w , F IPA , F EtOH , and F Acetone are the mass percentages of water, isopropanol, ethanol, acetone, etc. in the feed, respectively. The results obtained from the foregoing experiments can be further explained by the following analysis.

FTIR analysis: Figure 1 shows FT including PVA (a), CS (b), PVA/CS (c), PVA/CS-Ag ⁺ (d) and PVA/GA/CS-Ag ⁺ (e) pervaporation films -IR spectrum, in which a broad absorption band at 3100-3500 cm ^-1 is attributed to the stretching vibration of -OH. The peaks at 2833, 1324 and 843 cm ^-1 correspond to the stretching of CH and the bending of CH, respectively. The peak at 1086, 1415, 1719 cm ^-1 can be identified as a -CO group. In the chitosan map, the characteristic absorption band of 1570-1655 cm ^-1 is attributed to the indoleamine I, II and -C=O groups. The peaks of 1077, 1320 and 1154 cm ^-1 represent the stretching and glycosidic groups of CON, respectively. The peak at 1719 cm ^-1 of PVA/GA/CS-Ag ⁺ is smaller than the peak at the same position of (a), (c), and (d), which indicates that there is an interaction between GA and the film. Therefore, it was judged that the formation of an acetal (COC) bond was observed in the PVA/GA/CS-Ag ⁺ film.

TGA analysis: Thermogravimetric analysis of PVA, CS, PVA/CS, PVA/CS-Ag ⁺ and PVA/GA/CS-Ag ⁺ is shown in Figure 2. It proves that the introduction of silver ions (curve d) can greatly increase the heat resistance of the film, and the crosslinking effect (curve e) of glutaraldehyde can be used to better exert the optimum thermal stability of the film.

SEM Morphology & Elemental Analysis: Observe Figure 15a~h, Figure 16a~e and Figure 17a~e. When a higher content of silver ions, copper ions or iron ions is added, the obtained pervaporation film has no PVA and CS mixed. The resulting agglomerate phenomenon has a coarser network structure, which indicates that the presence of CS chelated by heavy metal ions such as Ag ⁺ , Cu ²⁺ , Fe ³⁺ promotes PVA/GA/CS-M ⁺ pervaporation film The intermolecular interactions thus increase their compatibility.

AFM Atomic Force Microscopy Analysis: Looking at Figure 18 and Figures 19a-c, the surface of the pure PVA film is relatively flat. When more CS is added, it will cause larger agglomerates. It can be seen from Fig. 20a~c, Fig. 21a~c and Fig. 22a~c that as the heavy metal ions such as Ag ⁺ , Cu ²⁺ and Fe ³⁺ increase, the agglomerates on the surface of the film become smaller and the surface roughness of the film It has also gradually increased, in line with the SEM test results.

Contact Angle Study: Water contact angles of PVA/GA/CS-Ag ⁺ pervaporation films with different levels of Ag ⁺ were measured. The observation results are shown in Fig. 3, showing that the contact angle decreases as the silver ion content increases. This silver ion has a high polarity, so in its presence, the PVA/GA/CS-Ag ⁺ pervaporation film has high hydrophilicity.

Swelling degree: In the present invention, chitosan chelated with heavy metal ions such as Ag ⁺ , Cu ²⁺ , Fe ^{3+ is} blended with PVA, and then cross-linked with glutaraldehyde to form a dehydration for organic aqueous solution. Pervaporation film. In general, crosslinkers can be used to prevent the polymer matrix from swelling due to water absorption, but this can result in a decrease in hydrophilic properties and a reduced flux of dehydration treatment. Due to the unshared electron pair of chitosan present in the amino nitrogen, it can adsorb heavy metal ions by chelation, and the polarity of the film is increased to greatly increase the water absorption of the film. Figure 4 shows the effect of water concentration in water/isopropanol mixture on the swelling degree of PVA/GA/CS-Ag ⁺ film with different contents of Ag ⁺ . The results show that PVA/GA/CS-Ag ⁺ penetration of higher silver ion content Evaporating the film and using a higher water/isopropanol ratio aqueous solution, the pervaporation film reflects a higher degree of expansion. The present inventors have found that the presence of CS chelated by heavy metal ions such as Ag ⁺ , Cu ²⁺ , Fe ³⁺ promotes the intermolecular interaction of PVA/GA/CS-M ⁺ pervaporation films, thereby obtaining better compatibility. The polymer matrix is capable of absorbing more water in a mixture of water/organic solvents while expanding itself without losing its network structure.

Pervaporation dehydration efficiency of PVA/GA/CS-Ag ⁺ film with different content of silver ions: water/different at 30 °C using PVA/GA/CS-Ag ⁺ film chelated with different content of silver ions Pervaporation dehydration process of propanol solution. The results show that the more the silver ions chelate, the higher the transmittance. This increase in polarity due to the addition of silver ions. Comparing Figure 4 with Figure 5, the results were found to be similar. In Figure 4, the increase in swelling is mainly due to an increase in water content; however, chelation of silver ions can also promote this effect. Similarly, more water content in the feed results in higher permeate, increased silver ion content, and a significant increase in permeate (Figure 5). We can conclude that the silver ions chelated on the CS molecule show the importance of dehydration of the isopropanol solution in the low water content feed, and the importance is also reflected in the very high water shown in Figure 6. Through concentration. No matter how many silver ions are introduced to prepare PVA/GA/CS-Ag ⁺ pervaporation film, the concentration of the permeate water can reach 99.99%, the silver ion concentration is 1.171×10 ^-1 mol., and the water permeation can reach 2 kg. /m ² h.

Comparison of the present invention with conventional data: a PVA-based pervaporation film was used for dehydration of an isopropanol solution at 10 ° C at 10 ° C. The results are shown in Table 1. In general, when the selection ratio is increased, the amount of transmission is lowered. The invention utilizes GA as a crosslinking agent, and sequesters CS as a precursor by heavy metal ions such as Ag ⁺ , Cu ²⁺ and Fe ³⁺ , which greatly improves the selection ratio and the permeation amount. With a silver ion content of 1.17 × 10 ^-1 mol., 10% by weight of water is fed, and a high separation efficiency with a separation factor of up to 89,991 can be achieved.

Table 1: Comparison of studies on the separation efficiency of modified PVA pervaporation films reported in the conventional literature for the dehydration of isopropanol.  <TABLE border="1" borderColor="#000000" width="85%"><TBODY><tr><td> Pervaporation film</td><td> Temperature.(°C) </td><td >% of feed water </td><td> Flux (Kg/m²h) </td><td> Separation factor</td><td> Remarks</td> <td> </td><td> </td></tr><tr><td> PVA-Gelatin (M-1) PVA- Gelatin (M-2) PVA- Gelatin (M-3) PVA- Gelatin (M-4) PVA-CA PVA/AA PVA-USF PVA-20/CS/USF PVA-40/CS/USF PVA-60/CS/USF PVA/GA PVA-NaAlg (25:75)/GA PVA -NaAlg (50:50)/GA PVA-NaAlg (75:25)/GA PVA/GA/CS-Ag⁺(2.4x10^-2mol) PVA/ GA/CS-Ag⁺(4.7x10^-2mol) PVA/GA/CS-Ag⁺ (7.1 x10^-2mol) PVA/GA/CS-Ag⁺(9.4 x10^-2mol) PVA/GA/CS-Ag⁺ (1.17 x10^-1mol) </td><td> 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 </td><td> 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 </td><td> 0.0319 0.0292 0.0352 0.0439 0.053 0.2 0.095 0.113 0.149 0.214 0.04 0.023 0.033 0.039 0.62 0.76 0.96 1.44 1.97 </td><td> 1160 179 1 929 848 291 300 77 17991 8562 6419 21 195 119 91 89991 89991 89991 89991 89991 </td><td> 知 知 知 知 知 习 习 习 习 习 习 习 习 习Knowing the case, the case, the case, the case </td><td> </td><td> </td></tr><tr height="0"><td></td><td></ Td><td></td><td></td><td></td><td></td><td></td><td></td><td></td ><td></td></tr></TBODY></TABLE>PVA, poly(vinyl alcohol); CA, citric acid; AA, proline; USF, urea formaldehyde/sulfuric acid; CS, shell poly Sugar; GA, glutaraldehyde; NaAlg, sodium alginate  

Specifically, according to the foregoing method for preparing a pervaporation film of the present invention, the silver ions may be replaced by copper ions, iron ions or other heavy metal ions, and the other methods are the same, thereby forming PVA/GA/CS-Cu ²⁺ or PVA/GA/CS-Fe ³⁺ (expressed as PVA/GA/CS-M ⁺ , where M ⁺ represents heavy metal ions) Pervaporation film, the physical properties such as tensile strength are as follows:

Tensile strength: PVA/CS, PVA/CS-Ag ⁺ , PVA/GA/CS-Ag ⁺ , PVA/GA/CS-Cu ²⁺ and PVA/GA/CS-Fe ³ were evaluated according to the measure of tensile strength. ⁺ Mechanical properties of the pervaporation film, the test data of which are listed in Table 2. When chitosan is blended in PVA, the tensile strength can be almost doubled, showing that PVA has good compatibility with CS, and there is a strong interaction between them. When Ag ^{+ is} introduced into the film, the tensile strength of the film can be greatly increased. Even without the addition of a crosslinking agent, the Ag ⁺ chelated CS and PVA molecules have a non-negligible interaction force. Helps the formation of a more compatible polymer matrix. The addition of CS to chelate Ag ⁺ can greatly improve the separation efficiency of organic water-soluble nights, and can also improve the mechanical strength of the polymer matrix. This can be clarified by comparing PVA/GA/CS with PVA/GA/CS-Ag ⁺ pervaporation film, in which the introduction of silver ions can greatly increase the tensile strength by 64.7%, showing CS and chelation with Ag ⁺ A strong interaction between PVAs, which also reflects an improvement in heat resistance properties. In addition, it can be seen from the data in Table 2 that the addition of copper ions and iron ions also showed results and characteristics similar to the addition of silver ions.

Table 2: Tensile strength and tensile elongation of pervaporation films  <TABLE border="1" borderColor="#000000" width="85%"><TBODY><tr><td> Pervaporation film</td><td> Tensile strength (Mpa) </td>< Td> stretch rate ( % ) </td></tr><tr><td> Pure PVA </td><td> 9 ± 2 </td><td> 166 ± 22 </td></ Tr><tr><td> PVA /CS </td><td> 17 ± 1 </td><td> 141 ± 10 </td></tr><tr><td> PVA /GA/CS </td><td> 17 ± 2 </td><td> 102 ± 17 </td></tr><tr><td> PVA /CS-Ag⁺(1.17 x10 ^-1mol. Ag⁺) </td><td> 130 ± 3 </td><td> 87 ± 14 </td></tr>< Tr><td> PVA/GA/CS-Ag⁺ (2.4 x10^-2mol. Ag⁺) </td><td > 90 ± 2 </td><td> 94 ± 17 </td></tr><tr><td> PVA/GA/CS-Ag⁺ (4.7 x10^{- 2}mol. Ag⁺) </td><td> 92 ± 3 </td><td> 94 ± 14 </td></tr><tr><td > PVA/GA/CS-Ag⁺ (7.1 x10^-2mol. Ag⁺) </td><td> 110 ± 2 </td><td> 91 ± 15 </td></tr><tr><td> PVA/GA/CS-Ag⁺ (9.4 x10<sup>-2</sup >mol. Ag⁺) </td><td> 145 ± 4 </td><td> 89 ± 11 </td></tr><tr><td> PVA/GA /CS-Ag<sup>+</sup > (1.17 x10^-1mol. Ag⁺) </td><td> 150 ± 3 </td><td> 89 ± 13 </td>< /tr><tr><td> PVA/GA/CS-Cu²⁺ (1.9 x10^-2mol. Cu²⁺) </td><td> 78 ± 3 </td><td> 60 ± 13 </td></tr><tr><td> PVA/GA/CS-Cu²⁺ (3.7 x10^-2mol. Cu²⁺) </td><td> 82 ± 3 </td><td> 54 ± 9 </td>< /tr><tr><td> PVA/GA/CS-Cu²⁺ (5.6 x10^-2mol. Cu²⁺) </td><td> 90 ± 4 </td><td> 50 ± 10 </td></tr><tr><td> PVA/GA/CS-Cu²⁺ (7.5 x10^-2mol. Cu²⁺) </td><td> 94 ± 2 </td><td> 48 ± 16 </td>< /tr><tr><td> PVA/GA/CS-Cu²⁺ (9.3 x10^-2mol. Cu²⁺) </td><td> 115 ± 5 </td><td> 45 ± 12 </td></tr><tr><td> PVA/GA/CS-Fe³⁺ (1 x10^-2mol. Fe³⁺) </td><td> 70 ± 5 </td><td> 72 ± 10 </td>< /tr><tr><td> PVA/GA/CS-Fe³⁺ (2 x10^-2mol. Fe³⁺) </td><td> 83 ± 2 </td><td> 71 ± 6 </td></tr><tr><td> PVA/GA/CS-Fe³⁺ (3 X10^-2mol. Fe³⁺) </td><td> 98 ± 1 </td><td> 68 ± 11 </td></tr ><tr><td> PVA/GA/CS-Fe³⁺ (4 x10^-2mol. Fe³⁺) </ Td><td> 110 ± 3 </td><td> 50 ± 9 </td></tr><tr><td> PVA/GA/CS-Fe³⁺ (5 X10^-2mol. Fe³⁺) </td><td> 120 ± 4 </td><td> 39 ± 13 </td></tr ></TBODY></TABLE>

In the pervaporation experiment, PVA/CS, PVA/CS-Ag ⁺ , PVA/GA/CS-Ag ⁺ , PVA/GA/CS-Cu ²⁺ and PVA/GA/CS-Fe ³⁺ films were evaluated. The experimental results of Fig. 5-8 can be respectively proved that the addition of Cu ²⁺ and Fe ³⁺ can effectively promote the water permeation amount without losing the selectivity as with the addition of Ag ⁺ . Further, the pervaporation film of the present invention can be used for dehydration of an aqueous ethanol solution and an aqueous acetone solution, in addition to an aqueous solution of isopropanol, which can be illustrated by the experimental results of Figs. This also shows a wide range of applications for the dehydration of numerous organic solutions.

In summary, the present invention uses GA as a crosslinking agent, and silver ions, copper ions and iron ions are respectively chelated to CS as a precursor, and blended with PVA, can successfully prepare PVA/GA/CS-Ag ⁺ , Pervaporation films such as PVA/GA/CS-Cu ²⁺ and PVA/GA/CS-Fe ³⁺ . The invention is used for dehydration of organic solutions, and has good mechanical properties and heat resistance. The present invention is supplied with an organic solution at 30 ° C, and is introduced into a pervaporation film by using silver ions, copper ions, iron ions or the like, and can effectively promote the permeation rate of water without losing its selectivity. For example, the present invention has a film having an Ag ⁺ content of 1.171×10 ^-1 mol., and it is found that at 30° C., dehydration of a high concentration isopropanol solution having a concentration of 90% by weight can be achieved. a separation factor of up to 89,991 and a transmission of up to 2 kgm ² h; whereas the prior art uses a PVA-based pervaporation film in the same situation, the results of which are shown in Table 1, in general, when the transmission is increased At the time, the selectivity is lowered, and thus the advantages of the present invention are known. In particular, the present invention also shows the effectiveness of dewatering of the feed at lower water levels, facilitating large scale purification applications.

The above detailed description is intended to be illustrative of a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and other equivalents and modifications may be made without departing from the spirit of the invention. Changes are intended to be included in the scope of the patents covered by the present invention.

no

Figure 1 shows (a) pure PVA, (b) pure CS, (c) PVA/CS, (d) PVA/CS-Ag ⁺ (Ag ⁺ : 1.17 x 10 ^-1 mol.) and (e) PVA/GA FTIR spectrum of /CS-Ag ⁺ (Ag ⁺ : 1.17 x10 ^-1 mol.). Figure 2 contains (a) pure PVA, (b) pure chitosan, (c) PVA/CS, (d) PVA/CS-Ag ⁺ (Ag ⁺ : 1.17 x10 ^-1 mol.) , (e) PVA TGA map of /GA/CS-Ag ⁺ (Ag ⁺ : 1.17 x10 ^-1 mol.). Figure 3 shows the contact angles of PVA/GA/CS-Ag ⁺ pervaporation films with different contents of Ag ⁺ . Figure 4 shows the effect of water concentration in a water/isopropanol mixture on the degree of swelling of PVA/GA/CS-Ag ⁺ films with different Ag ⁺ contents. Figure 5 is a graph showing the permeation of a PVA/GA/CS-Ag ⁺ pervaporation film having different contents of Ag ⁺ at 30 ° C in various water/isopropanol mixtures. Figure 6 shows the effect of Ag ⁺ content on the pervaporation performance of a water/isopropanol mixture at 30 ° C (90 wt% feed isopropanol concentration) through a PVA/GA/CS-Ag ⁺ pervaporation film. Figure 7 is a graph showing the amount of PVA/GA/CS-Cu ²⁺ pervaporation film having different contents of Cu ²⁺ at 30 ° C in various water/isopropanol mixtures. Figure 8 is a graph showing the permeation of a PVA/GA/CS-Fe ³⁺ pervaporation film having different contents of Fe ³⁺ at 30 ° C in various water/isopropanol mixtures. Figure 9 is a graph showing the permeation of PVA/GA/CS-Ag ⁺ pervaporation films with different contents of Ag ⁺ at 30 ° C in various water/ethanol mixtures. Figure 10 is a graph showing the permeation of PVA/GA/CS-Ag ⁺ pervaporation films with different contents of Ag ⁺ at 30 ° C in various water/acetone mixtures. Figure 11 shows the permeation of PVA/GA/CS-Cu ²⁺ pervaporation films with different contents of Cu ²⁺ at 30 ° C in various water/ethanol mixtures. Figure 12 is a graph showing the amount of PVA/GA/CS-Cu ²⁺ pervaporation film having different contents of Cu ²⁺ at 30 ° C in various water/acetone mixtures. Figure 13 is a graph showing the permeation of PVA/GA/CS-Fe ³⁺ pervaporation films with different contents of Fe ³⁺ at 30 ° C in various water/ethanol mixtures. Figure 14 is a graph showing the permeation of PVA/GA/CS-Fe ³⁺ pervaporation films with different contents of Fe ³⁺ at 30 ° C in various water/acetone mixtures. Figures 15a-h include (a) pure PVA, (b) PVA/CS, (c) PVA/GA/CS-Ag ⁺ (Ag ⁺ : 2.4x10 ^-2 mol.), (d) PVA/GA/CS -Ag ⁺ (Ag ⁺ : 4.7x10 ^-2 mol.), (e) PVA/GA/CS-Ag ⁺ (Ag ⁺ : 7.1 x10 ^-2 mol.), (f) PVA/GA/CS-Ag ⁺ ( Ag ⁺ : 9.4 x10 ^-2 mol.), (g) SEM image of PVA/GA/CS-Ag ⁺ (Ag ⁺ : 1.17 x10 ^-1 mol.) film and (h) EDS chart (Ag ⁺ : 1.17 x10 ^{- 1} mol.). Figures 16a-e include (a) PVA/GA/CS-Cu ²⁺ (1.9 x 10 ^-2 mol. Cu ²⁺ ), (b) PVA/GA/CS-Cu ²⁺ (3.7 x 10 ^-2 mol. Cu ²⁺ ), (c) PVA/GA/CS-Cu ²⁺ (5.6 x10 ^-2 mol. Cu ²⁺ ), (d) PVA/GA/CS-Cu ²⁺ (7.5 x 10 ^-2 mol. Cu ^{2+ )} And (e) SEM images of PVA/GA/CS-Cu ²⁺ (9.3 x 10 ^-2 mol. Cu ²⁺ ) films. Figures 17a-e include (a) PVA/GA/CS-Fe ³⁺ (1 x 10 ^-2 mol. Fe ³⁺ ), (b) PVA/GA/CS-Fe ³⁺ (2 x 10 ^-2 mol. Fe ³⁺ ), (c) PVA/GA/CS-Fe ³⁺ (3 x10 ^-2 mol. Fe ³⁺ ), (d) PVA/GA/CS-Fe ³⁺ (4 x10 ^-2 mol. Fe ³⁺ And (e) SEM images of PVA/GA/CS-Fe ³⁺ (5 x 10 ^-2 mol. Fe ³⁺ ) films. Figures 18a-1 to a-2 are AFM images of a pure PVA film. Figures 19a~c include (a-1~a-2) CS/PVA ratio of 1/5, (b-1~b-2) CS/PVA ratio of 3/5, (c-1~c-2) The AFM map of the different CS/PVA weight ratio films with a CS/PVA ratio of 5/5. 20a~c include (a-1~a-2) Ag ⁺ : 2.4x10 ^-2 mol. , (b-1~b-2) Ag ⁺ : 7.1 x10 ^-2 mol. , (c-1~c -2) Ag ⁺ : 1.17 x10 ^-1 mol. AFM pattern of PVA/GA/CS-Ag ⁺ film with different Ag ⁺ addition amount. Figure 21a~c includes (a-1~a-2) Cu ²⁺ : 1.9 x10 ^-2 mol. Cu ²⁺ , (b-1~b-2) Cu ²⁺ : 5.6 x10 ^-2 mol. Cu ^{2 +} , (c-1~c-2) Cu ²⁺ : 9.3 x10 ^-2 mol. AFM pattern of PVA/GA/CS-Cu ²⁺ film with different Cu ²⁺ addition amount. Figures 22a~c include (a-1~a-2) Fe ³⁺ : 1 x10 ^-2 mol. , (b-1~b-2) Fe ³⁺ : 3 x10 ^-2 mol. , (c-1 ~c-2) Fe ³⁺ : 5 x10 ^-2 mol. AFM pattern of PVA/GA/CS-Fe ³⁺ film with different Fe ³⁺ addition amount.

Claims (9)

A method for preparing a high permeability and high selectivity pervaporation film for dehydration of an organic solution, comprising the steps of: preparing polyvinyl alcohol (PVA), chitosan (CS) and glutaraldehyde (GA); The unit weight of the chitosan is dissolved in nine unit weight of deionized water, and stirred at room temperature for 7 to 10 hours to form a solution; a salt such as silver nitrate or copper nitrate or ferric nitrate is added to the solution for Forming liquid A and continuing to stir; one unit weight of the polyvinyl alcohol is dissolved in nine unit weight of deionized water, and stirred at 70 ° C for 20 to 24 hours to form liquid B; the liquid A and the liquid B Mix well and stir for at least 2 hours to form a mixed solution C; stir at 70 ° C for at least 1 hour, place the mixed solution C in a polyethylene petri dish, and dry it in an oven at a temperature of 25 ° C to 50 ° C for 1 day. Glutaraldehyde is added to form a pervaporation film that is highly permeable to the dehydration of the organic solution. The method for preparing a pervaporation film according to claim 1, wherein the organic solution is an aqueous solution of isopropanol, an aqueous solution of ethanol, an aqueous solution of acetone or another aqueous solution of an organic solvent. The method for producing a pervaporation film according to claim 1, wherein the unit weight is 5 g, and the nine unit weight is 45 g. The method for preparing a pervaporation film according to claim 1, wherein the chitosan is dissolved in ionized water at room temperature for 8 hours, and the PVA is dissolved in deionized water for 24 hours. The method for preparing a pervaporation film according to claim 1, wherein when a relatively high concentration of silver ions or copper ions or iron ions is added, a film having a relatively uniform network structure can be obtained, which means CS Chelated silver ions or copper ions or iron ions interact with PVA to improve the compatibility of CS with PVA. The method for preparing a pervaporation film according to claim 1, wherein the cross-linking effect of glutaraldehyde is added to make the pervaporation film exhibit optimal thermal stability. The method for preparing a pervaporation film according to the first aspect, wherein the Ag ⁺ or Cu ²⁺ or Fe ³⁺ or other heavy metal ions chelate the CS system to promote the intermolecular interaction of the pervaporation film, Further, a highly compatible polymer matrix is obtained and allowed to absorb more water in a mixture of water/organic solvent systems, thereby swelling itself without losing its network structure. A pervaporation film formed according to the preparation method of claim 1. A highly selective and highly permeable pervaporation film for dehydration of an organic solvent is formed by using glutaraldehyde as a crosslinking agent for polyvinyl alcohol and chitosan, and adding silver ions or copper ions or iron ions.